Mechanics
Right now, the mechanics for Earth-based players have been kept simple.
You must gather ore using Worker-class units. Then process the ore into metal with OreProcessor buildings. Finally, submit the metal via OrbitalMassDriver to assist space forces.
Defence
If, for some reason, your units or buildings are threatened...
Soldier-class units have been made available, with varying weaponry.
All units will automatically attack the nearest target.